As I've experienced ...

Using a 64bit OS is not a signal to upgrade everything to 64bit.
You can easily use a 32bit FireBird server and client on a 64bit OS.

But going from FB1 to FB2.5 is a whole other thing.
You will have to check your database several times - to ensure that it will be able to run on the new Disk Structure.

There are several good advices/considerations on upgrading on Firebirdsql.org -> http://www.firebirdsql.org/file/documentation/release_notes/html/install210.html#install2-win-readfirst

Kind Regards
Bimmer_R

--- In firebird-support@yahoogroups.com, Frank Schlottmann-Gödde <frank@...> wrote:
>
> Am 30.04.2013 14:18, schrieb Lepage, Pierre:
> > Hi,
> >
> > We are using Firebird Client 1.0 on one or a lot of computers in the
> > company.
> >
> > Actually, we analyze the situation because we plan to migrate every
> > computers in the company from Windows XP to Windows7 64bits.
> >
> > We need to know if Firebird Client 1.0 will run under Win7 64bits or
> > if we need to download Firebird 2.5.
>
> I haven't tried it, but it should run. Although, if you want to convert
> your client programs to 64bits you will need to use a 2.5 64bit
> fbclient.dll.
>
> > I need to be sure that Firebird 2.5 is an upgrade of Firebird Client
> > 1.0 because it's not mention on your website.
>
> The 2.5 fbclient.dll is a bit more than an upgrade and should be able to
> connect to ancient Fb 1.0 installations
>
> > Could you confirm all of that to me?
>
> Well, a real confirmation will need a test with your client programs and
> your servers. I haven't seen a 1.0 installation for about ten years.
>
> hth
> Frank
>
> --
> "Fascinating creatures, phoenixes, they can carry immensely heavy loads,
> their tears have healing powers and they make highly faithful pets."
> - J.K. Rowling
>